Unitary multiple spark-gap device



Dec. 21, 1948. E. a. F. ARNOTT ET AL 2,

UNI'IARY MULTIPLE SPARK-GAP DEVICE Filed Oct. 2, 1944 INVENTORS ATTORNEY 7-0 m/aaar/Na 50 uece Patented Dec. 21, 1948 UNITARY MULTIPLE SPARK 'GAPDEi/ICE Edward G. F. Arnott, Upper Montclair, and Clarence E. Dawley, Bloomfield, N. J.,- assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application October 2, 1944, Serial No. 556,755

6 Claims. 1

The present invention relates to spark-gap devices and more particularly to such devices which are operable at high voltage for the pulsing of electrical energy.

Devices of this type are now commonly employed for controlling the current in radar modulator circuits and have heretofore required from two or three or more such spark-gaps in series. This has necessitated the occupation of considerably more space than desired, thus increasing the total size and weight of the complete equipment.

It is accordingly an object of the present invention to provide a single spark-gap device having a plurality of electrodes and which operates in such manner that a plurality of spark-gap devices connected in series is eliminated.

Another object of the present invention is the provision of a unitary spark-gap device provided with a plurality of electrodes between which two or more arc discharges occur in series, thus eliminating the necessity for the employment of a plurality of individual spark-gaps in amodulator circuit.

A further object of the present invention is the provision of a unitary spark-gap device which will replace a plurality ofindividualspark-gap devices connected in series.-

Still further objects of the present invention will become obvious to those skilled in the art by reference to the accompanying drawing wherein:

Figure 1 is a sectional view of a multiple sparkgap device constructed in accordance with the present invention;

Figure 2 is a sectional view taken on the line II-II of Fig. 1;

Figure 3 is a sectional view of a slight modification which the spark-gap device of the present invention may take;

Figure 4 is a schematic diagram showing the connections to the various electrodes of the structure of Fig. 1 so that the unitary gap operates to eliminate the necessity for a plurality of series connected spark-gaps.

Referring now to the drawing in detail, the spark-gap device as shown in Fig. 1 comprises an envelope shown generally at 5 provided with a plurality of electrodes therein. For example, one such electrode 6 is formed as a cylinder of suitable metal, such as aluminum or the like, surrounded by a collar 1, formed of suitable metal having a coeificient of expansion similar to that of glass, such as the alloy known to the art as Kovar and soldered or welded to the cylindrical electrode 6. As shown, this collar-T is slightly less in cross-section thanthat ofthe cylindrical electrode 6, and the ends of this collar forms an hermetic seal with a vitreous sleeve 8, while the other end of the collar is similarly sealed to a further vitreous sleeve 9. The vitreous sleeve 8 is in turn hermetically sealed to an annular Kovar collar ill provided with a flanged portion 12 of slightly reduced diameter to which a cylindrical metallic electrode [3 of aluminum or the like is rigidly secured in any suitable manner, such as by soldering, welding or the like. A header member M is also similarly secured to the interior surface of the flanged portion it, which thus forms a closure for this end of the device and an exhaust tubulation I5 is provided in the header member 54 for the purpose of evacuating the device and filling with the desired gas, such as a mixture of hydrogen and 20% argon at substantially atmospheric pressure.

The vitreous sleeve ii is likewise hermetically sealed to an annular Kovar collar It having a flanged portion ll, the latter of which is of slightly less diameter than the flanged portion 52 of the collar It, with this collar 16' likewise rigidly supporting a cylindrical metallic electrode I8, of aluminum or the like, in the same manner that the collar it supports the electrode l3. The peripheral surface of the collar it is in turn hermetically sealed to a vitreous insulating sleeve LB with such sleeve being closed at its other end by a Kovar cup or the like 26, which thus also closes the end of the hermetically sealed device 5.

An anode electrode 22 formed of steel rod or the like, which for all intents and purposes may also be considered as cylindrical, is welded, brazed, or soldered to the Kovar cup 26. The structure of this anode electrode 22 is shown and described in our previously issued Patent No. 2,411,241, granted November 19, 1946, and further detailed description her'ein'is believed unnecessary except to state that because of its configuration the potential gradient at the anode is more uniformly distributed over the anode surface, thus eliminating concentration of the arc discharge during operation of the device.

By referencenow to Fig. 4 the mannerin' which a potential is supplied to the device of Fig. 1 is therein shown and which eliminates the necessity for employing a plurality of individual spark-gap devices. The spacing between the various electrodes is such that the same definite minimum voltage is required to break down the gap between each pair. For example, assuming a potential of 12' kilovolts is applied from a suitable source L1 to L2 between the electrodes 6 and 22, and such potential is divided in any suitable manner, with 3 4 kv. being impressed across the electrodes 22 and I8, 4 kv. between the electrodes I8 and I3, and 4 kv. between the electrodes 13 and 6, as shown in Fig. 4.

These kilovoltages are arbitrary figures selected solely for illustrative purposes and may be varied to suit conditions by altering the electrode spacings. In the example shown, the kilovoltage applied is insuificient to break down any one of the gaps which may require say a minimum of 6 kv. If now a triggering voltage of more than 4 kv. is applied from a separate triggering source of opposite sign to that of L1, as indicated by the legend (the opposite side of the trigger source being grounded and hence con nected to electrode 22), at the electrode I8, this voltage is added to the 8 kv. already across the upper two gaps and is sufficient to break them down with an attendant discharge between the electrodes l8-l3 and l3-6. The electrode l8 thus immediately assumes the same potential as that of the electrode 6 with respect to the electrode 22 giving 12 kv. thereacross causing substantially simultaneous breakdown of the gap between the electrodes 18 and 22 and a discharge thereacross.

Accordingly by triggering the upper gaps in the series between the electrodes l8--l3 and l3-6, the entire device breaks down almost instantaneously by the occurrence of an arc discharge across the gap between each pair of electrodes, thus enabling the unitary device to supply a current therethrough to a load from the electrode 6 to the opposite end electrode 22 of the series.

In Fig. 3 a structure is shown which is identi cal to the spark-gap device as shown in Figs. 1, 2 and l, except that it provides only two gaps instead of three as in these latter figures. To this end the electrode 6 is entirely dispensed with and the vitreous sleeves 8 and 9 are formed into a single sleeve 23 but in all other respects the structure of Fig. 3 is identical to that described relative to Fig. 1 and operates in the same manner.

From the foregoing it is believed to be obvious to one skilled in the art that a unitary sparkgap device is herein provided which eliminates the necessity for a plurality of series connected individual devices as formerly required, with material reduction in the space and weight of the equipment with which such devices are employed. Moreover, since the electrodes are concentrically disposed with respect to each other and the cathode electrodes being of cylindrical configuration provide ample surface area for the accumulation of sputtered material thereon without materially affecting the electrode spacing and hence the breakdown voltage of the device during its entire useful life. In addition, the employment of Kovar cups of relatively large diameter allows the device to be readily assembled and the parts to be accurately aligned and sealed in the manner shown and claimed in the copending application of Ward W. Watrous, Jr., Serial No. 521,807, filed February 10, 1944, issued June 17, 1947, as U. S. Patent No. 2,422,324, and assigned to the same assignee as the present invention.

Although several embodiments of the present invention have been herein shown and described, it is to be understood that still further modifications of the device may be made without departing from the spirit and scope of the appended claims.

We claim:

l. A unitary high voltage spark-gap device for supporting a plurality-of high voltage are discharges in series relationship comprising a sealed envelope provided with an ionizable gas therein at relatively high pressure, and a plurality of concentrically disposed metallic electrodes in said envelope having their parallel adjacent surfaces spaced equi-distant from each other throughout substantially their entire respective lengths to cause the arc initiating voltage between adjacent electrodes to remain uniform throughout the useful life of said device.

2. A unitary high voltage spark-gap device for supporting a plurality of high voltage arc discharges in series relationship comprising a sealed envelope provided with an ionizable gas therein at substantially atmospheric pressure, a metallic rod-like electrode disposed coaxially with respect to the longitudinal axis of said device, and a plurality of cylindrical metallic electrodes concentrically and telescopically disposed relative to each other and to said rod-like metallic electrode with said electrodes having their parallel adjacent surfaces spaced equi-distant from each other throughout substantially their entire respective lengths to cause the arc initiating voltage between adjacent electrodes to remain uniform throughout the useful life of said device.

3. A unitary high voltage spark-gap device for supporting a plurality of arc discharges in series relationship comprising a sealed envelope, a plurality of concentrically disposed electrodes in said envelope having their parallel adjacent surfaces spaced equi-distant from each other throughout substantially their entire respective lengths, an ionizable gas at relatively high pressure in said envelope, means for applying a potential between each pair of electrodes of insufiicient magnitude to cause a discharge therebetween, and means for applying a supplemental potential between one pair of electrodes of sufficient magnitude to cause an arc discharge with an attendant substantially simultaneous series of arc discharge of uniform voltage between the remaining adjacent electrodes of said device.

4. A unitary high voltage spark-gap device for supporting a rod-like plurality of high voltage are discharges in series relationship comprising a sealed envelope provided with an ionizable gas therein at relatively high pressure, a rod-like metallic electrode coaxially disposed with respect to the longitudinal axis of said device, a plurality of cylindrical metallic electrodes concentrically and telescopically disposed relative to each other and to said rod-like metallic electrode with said electrodes having their parallel adjacent surfaces spaced equi-distant from each other throughout substantially their entire respective lengths,

means for applying a potential between each pair of electrodes of insuificient magnitude to cause a discharge therebetween, and means for applying a supplemental potential between one pair of electrodes of sufiicient magnitude to cause an arc discharge with an attendant substantially simultaneous series of arc discharge between the remaining electrodes of said device.

5. A unitary high voltage spark-gapdevice for supporting a plurality of high voltage are discharges in series relationship comprising a sealed envelope provided with an ionizable gas therein at substantially atmospheric pressure, a rod-like metallic electrode coaXially disposed with respect to the longitudinal axis of said device, a plurality of cylindrical metallic electrodes concentrically and telescopically disposed relative to each other and to said rod-like metallic electrode with said electrodes having their parallel adjacent surfaces spaced equi-distant from each other throughout substantially their entire respective lengths to cause a uniform voltage drop between the latter, and a support for each of said electrodes and forming an hermetic seal with said envelope.

6. A unitary high voltage spark-gap device for supporting a plurality of high voltage are discharges in series relationship comprising a sealed envelope formed in part of vitreous material and provided with an ionizable gas therein at relatively high pressure, a rod-like metallic electrode coaxially disposed with respect to the longitudinal axis of said device, a plurality of cylindrical me tallic electrodes concentrically and telescopically disposed. relative to each other and to said rodlike metallic electrode With said electrodes having their parallel adjacent surfaces spaced equidistant fI'G-lll each other throughout substantially their entire respective lengths to cause a uniform voltage drop between the latter, and a metallic support for each of said electrodes having a coeificient of expansion simulating that of the vitreous part of said envelope and forming an hermetic seal therewith.

EDWARD G. F. ARNOTT. CLARENCE E. DAWLEY.

EENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

